連続ねじり加工を行ったAl-Mg合金の耐孔食性

概要

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The pitting corrosion resistance of an Al-Mg alloy produced by continuous rotation evolutional control (CREO) was investigated by means of polarization curves in solutions containing 0.1mol/L Na2SO4 and 300ppm Cl−, and by surface analysis. The pitting potential of Al-Mg alloy was evidently shifted to the noble direction by CREO, and the time required for initiating pitting corrosion of the Al-Mg alloy while kept at a constant potential of −0.1V was longer with CREO than without, indicating improvement in the pitting corrosion resistance by application of CREO. Al-Mg alloy contained such precipitates as Al-Fe intermetallic compounds and trace quantities of Si, around which pitting corrosion occurred. CREO pulverized these precipitates. The time-dependence of corrosion potential and the polarization resistance determined by the AC impedance technique suggest that the resistance of Al oxide films was increased with CREO. Therefore, it was concluded that the improvement of pitting corrosion resistance of Al-Mg alloy with CREO was caused by both decreasing the size of the precipitates which acted as cathodes during corrosion and increasing the film resistance of Al oxide.
一般社団法人表面技術協会の論文
2008-06-01